Is Diatom Richness Responding to Catchment Glaciation? a Case Study from Canadian Headwater Streams

J. Limnol., 2012; 71(1): 72-83 DOI: 10.4081/jlimnol.2012.e7

Is diatom richness responding to catchment glaciation? A case study from Canadian headwater streams

Doris GESIERICH*, and Eugen ROTT

Institute of Botany, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria *Corresponding author: [email protected]

ABSTRACT Due to global change affecting glaciers worldwide, glacial streams are seen as threatened environments deserving specific scientific interest. Glacial streams from the Coast Range and Rocky Mountains in British Columbia and at the border to Alberta were investigated. In particular glacial streams and downstream sites in the Joffré Lakes Provincial Park, a near by mountain river and two large glacial streams in the Rocky Mountains (Kootenay Range, Jasper National Park) were studied. Regardless of a high variability of catchment glaciation (1 to 99%) thin organic biofilms with firmly attached diatom frustules of the genera Achnanthidium, Psammothidium, En- cyonema, Gomphonema and fragilaroid taxa were found in all cases. In spite of fundamentally different geological conditions between the Coast Range sites and the Rocky Mountain sites, the pioneer taxon Achnanthidium minutissimum (with a slimy long ecomorph) was dominating quantitatively in most of the glacier stream samples together with the rheobiontic Hannaea arcus. Individual glacier stream samples were characterized by the dominance of Achnanthidium petersenii and Gomphonema calcifugum/Encyonema latens. The diatom community analysis (cluster analysis) revealed the expected separation of glacier stream sites and sites of the lower segments of the river continuum (e.g., dominance of Diatoma ehrenbergii in the mountain river). In the Joffré area, the total species richness of turbid glacial streams close to the glacier mouth was significantly lower than in the more distant sites. The two largest glacial streams in the Rocky Mountains showed divergent results with a remarkable high species richness (43 taxa) at the Athabasca River origin (Co- lumbia Icefield) and low diversity in Illecillewaet river (9 km downstream the glacier mouth). From the biogeographical point of view the dominant taxa comprised mainly widespread pioneer species coping best with the unstable conditions, while the subdominant taxa comprised taxa specific for pristine arctic-alpine or high altitude habitats (e.g., Psammothidium grischunum). Almost 50% of the taxa were classified as oligo- to oligo-mesotraphentic and approximately 20% as endangered or extremely rare.

Key words: hydrobiology, glacial streams, oligotrophy, diatoms, biodiversity.

Received: August 2011. Accepted: October 2011.

INTRODUCTION Alpine River and Stream Ecosystem, Brown et al. 2009, ACQWA – Assessing Climate impacts on the Quantity and In mountain ranges worldwide the glaciation of quality of Water, http://www.acqwa.ch/), benthic algae are drainage basins has a strong influence on the ecology of the adjacent glacial streams, specific high-alpine head-water still a quite neglected component of investigations (e.g., types. Glacial streams show unique features, characterized Brittain, and Milner 2001, Cantonati et al. 2001). For high by large seasonal and diurnal run-off fluctuations, strong altitudes in the Alps mainly two major stream types can be longitudinal temperature gradients, restricted organic re- differentiated, (A) kryal (glacialmelt dominated) and (B) sources and temporarily enhanced sediment transport. They krenal (groundwaterfed) streams (Ward 1994, Füreder provide extremely harsh environments for benthic algae 1999). The kryal stream section is characterised by con- leading to the selection of a specific diatom species spec- stantly low temperatures (Tmax<4°C) and extreme diurnal trum. Due to missing higher vegetation channel, shading is fluctuations of run-off in summer due to the diurnal air tem- low and organic matter input limited (allochthonous of or- perature variation in high altitudes of the glaciated areas. ganic matter/nutrients). Eventual nutrient pulses originating These run-off variations can be higher than the annual from catchment washout are modified by temporal runoff runoff variations. Additional typical features are extremely pulses during snowmelt and/or from glacial flour during turbid waters from glacial silt and low channel stability melting peak flows in summer (Rott et al. 2006). close to the glacier mouth (Milner, and Petts 1994, Ward Although several attempts were undertaken to extend 1994). The glaciorhithral zone adjacent to the kryal seg- the knowledge on alpine stream ecosystems (EU-funded ment is highly influenced by glacial runoff at some distance projects: AASER – Arctic and Alpine Stream Ecosystem from the glacier mouth providing unstable substrate, high Research focusing on glacial stream ecosystems across Eu- sediment loads and low summer temperatures (Füreder rope, Brittain et al. 2000; ARISE – A classification tool for 1999). Diatom richness in glacial streams 73

Fig. 1. Geographic location of the sampling sites (1-12) in SW Canada (British Columbia, Alberta); a) overview, b) position of the sampling sites in the provinces of British Columbia and Alberta, c) detailed map of the sites 1-9 in Joffré Lake Provincial Park (MG – Matier glacier, SG – Stonecrop glacier, TG – Tszil glacier, black spots indicate Upper, Middle and Lower Joffré Lake).

Studies on benthic algae in alpine streams in general linity lakes throughout the NE United States and SE and glacial streams in particular are rare. Most recent stud- Canada are already given (Camburn, and Charles 2000). ies were conducted in central and northern Europe dealing The baseline hypotheses for the present study that only with the influence of glacial dynamics on benthic algae specific adapted algae may grow in glacier streams has communities (e.g., Uehlinger et al. 1998; Cantonati et al. been derived from periphyton studies of glacier streams in 2001; Bürgi et al. 2003; Gesierich, and Rott 2004; Hansen the European Eastern Alps (Rotmoos, Ötztal and National et al. 2006; Rott et al. 2010; Uehlinger et al. 2010) and the Park Hohe Tauern, Austria) (Rott et al. 2006). Here most Himalaya (Jüttner et al. 2000). More studies on benthic algae groups except diatoms were considerably reduced in algae and diatoms under extreme environment conditions richness at distances of less than 1 km from the glacier were carried out in the Antarctic (e.g., Howard-Williams et mouth (Rott et al. 2006). al. 1986; Vincent, and Howard-Williams 1989) and Arctic This actual case study therefore follows five major region (Elster et al. 1997; Antoniades, and Douglas 2002), questions: (1) How close to the permanent ice are diatoms respectively. Although excellent expertises of diatoms from found in glacier streams? (2) Which taxa are present? (3) rivers in N-America have been accumulated in recent years Is the taxonomic composition specific or variable? (4) Is (Anderson, and Carpenter 1998; Potapova, and Charles the taxonomic composition affected by glacier size or other 2003; Bahls 2004, 2005; Carlisle et al. 2008; Potapova, and factors? and (5) Can glacial segments be differentiated from Carlisle 2011; USGS NAWQA Program 2011), small other sites within the river continuum? streams in pristine and remote areas, and especially glacial streams have not yet been in focus of interest, even though MATERIALS AND METHODS they can serve as remote lotic environment hotspots for bio- Twelve sites were sampled in August 2006 in SW diversity conservation (Cantonati et al. 2001). For the Canada (British Columbia, Alberta) (Figs 1a and b). The unglaciated Appalachians (East coast) an extended biodi- sites comprise the uppermost sections of variable sized gla- versity inventory including diatoms has been made for the cial streams (from a few l s 1 to more than 5 m3 s-1), glacial Great Smoky Mountains National Park (Johansen et al. lake outflows and a rhithral mountain river. Catchment 2004), representing data based on the survey of spring areas and catchment glaciation varies along a broad range streams mainly from crystalline rocks serving as a reference (1 to 99%) (Tab. 1). Most sites (sites 1-9) were situated in to the present study. In multiple studies diatoms are widely Joffré Lakes Provincial Park (14.6 km2) 70 km SW from used as indicators for environmental changes, in terms of Lillooet in the Eastern part of Coast Mountains region of climate change or acidification (e.g., Smol, and Störmer British Columbia (Fig. 1c). The bedrock is composed 2010), in this context complex information for low-alka- mostly of cretaceous origin granite and granodiorite 74 D. Gesierich, and E. Rott

Tab. 1. Location and characteristics of the investigated sites (1-12). Nr: Number of the sampling site; T: stream type (GR – glaciorhithral, KR - krenal, KT - kryal turbid, R – rhithral); Alt: altitude; Size: catchment size; Glac: catchment glaciation; Run – runoff). Site Nr T Latitude N Longitude W Alt Size Glac Run (m) (km2) (%) (m3) Matier Glacier Creek, NE 1 KT 50°20’39.77’’ 122°28’11.61’’ 1780 0.49 48.2 0.2 Matier Glacier Creek, upper part 2 KT 50°20’40.62’’ 122°28’26.00’’ 1780 0.89 92.4 0.1 Matier Glacier Creek, lower part 3 KT 50°20’40.62’’ 122°28’26.00’’ 1600 0.94 88.0 0.6 Stonecrop glacier, SW of campground 4 KR 50°20’40.48’’ 122°28’35.89’’ 1580 0.32 44.6 0.1 Tszil glacier stream NE, under waterfall 5 KT 50°19’59.94’’ 122°29’14.55’’ 1900 0.14 45.0 <<0.1 Tszil glacier mouth + snow field 6 KT 50°19’50.21’’ 122°29’20.98’’ 1920 0.10 47.3 <<0.1 Tszil stream down near lake 7 GR 50°20’44.57’’ 122°28’47.53’’ 1580 1.27 8.9 0.2 Upper Joffre Lake outlet, cascade 8 GR 50°21’04.48’’ 122°28’49.65’’ 1490 3.88 33.9 1.0 Outflow Lower Joffre Lake, near parking 9R50°22’06.68’’ 122°29’56.59’’ 1210 5.47 24.0 1.0-2.0 Cayoosh Creek 10 R 50°36’53.67’’ 122°06’13.92’’ 950 100.00 1.0 3.0-5.0 Illecillewaet, near campground 11 KT 51°15’58.91’’ 117°29’59.03’’ 1240 239.20 34.6 3.0-5.0 Athabasca River origin 12 KT 52°12’45.30’’ 117°14’02.15’’ 2000 300.00 99.0 3.0-5.0

(British Columbia’s Online Digital Geology Map, lated to Paleozoic Cambrian to Ordovician strata of the http://www.empr.gov.bc.ca/Mining/Geoscience/BedrockM Rockies (limestone, dolomite, quartzite and other carbona- apping/Pages/BCGeoMap.aspx). ceous minerals). Site 12 is situated approx. 100 m down- Most of these sites are strongly affected by glacial silt stream the glacier mouth of Columbia Icefield at an altitude that is suspended in the water. Matier glacier, the largest of 2000 m a.s.l. and is characterised by 99% catchment glacier in the Joffré Group, is the origin to waters of sites glaciation from a total icefield of 300 km2. 1-3, whereas site 4 is apparently indirectly influenced by Epilithic diatoms were collected following standard the small Stonecrop rock glacier, at 1 km distance from the procedures (e.g., European Committee for Standardization origin with less glacial silt particles than the others. Sites 2004), based on combined wash-samples from stones. 5-6 are influenced by Tszil glacier to various extend. Two Samples were cleaned using hydrochloric acid and 30% hy- sites (8 and 9) were sampled downstream the existing lake drogen peroxide. For light microscopy (LM) the mounting basins of Middle and Lower Joffré Lakes within pine of the cover slips was done using Naphrax®, a mountant forests. Elevation gain from site 9 at the outflow of the low- with a high refractive index ([R.I.]=1.74). An Olympus est Joffré Lake near the parking area to site 6 near the gla- BX50-microscope equipped with a micro-camera (Olym- cier mouth of Tszil Glacier is about 710 m. The sampling pus PM-C35B) was used for documentation. For scanning area is characterised by the three small, turquoise blue Jof- electron microscopy (SEM), subsamples of the diatom sus- fré lakes situated right below the massive Joffré Glacier pension were air-drying on glass cover slips and fixed on Group. aluminium stubs with silver seal. The stubs were sputter- Site 10 is located approx. 30 km NE of Joffré area, coated with gold and examined in a Hitachi S-4700 Field around 10 km SW from Lillooet in the Cayoosh Range, the Emission Scanning Electron Microscope (FESEM) as well northernmost section of the Lillooet Ranges in the Coast as in a Hitachi S-2600N Variable Pressure Scanning Elec- Mountains in British Columbia. Cayoosh Creek is a NE tron Microscope (VPSEM). flowing tributary of the Seton River and represents a clear The LM examinations were carried out at ¥1000 mag- water mountain stream with minor glacial influence (1% nification and at the lowest taxonomical level. A minimum catchment glaciation) sampled at an altitude of 950 m a.s.l. of 300 valves were counted per slide for calculation of the The Illecillewaet River (site 11) as part of the Columbia relative abundance, with the exception of Site 6, near Tszil River watershed, is fed by Illecillewaet Glacier in Glacier Glacier mouth, which was extremely poor in diatom valves National Park (1349 km2) in the NW part of the Kootenay (count of 100). The whole cover slip was screened after Rocky Mountains. The catchment is a mixture of marble, counting to characterise the actual species spectrum present dolomite, limestone and shists of Cambrian to Devonian at each site, and every new taxon was added to the species and Upper Proterozoinc to Cambrian origin bedrocks and list with an absolute count of 1 individual (see Guidelines alluvial formations in the valley including proterozoic ori- for biological water quality assessment in Austria: Part Phy- gin diorites (British Columbia’s Online Digital Geology tobenthos, Pfister, and Pipp 2010). The relative abundance Map, http://www. empr.gov.bc.ca/Mining/Geoscience/ of each taxon was then indicated with: e - eudominant BedrockMapping/ Pages/BCGeoMap.aspx). (>50%), d - dominant (50–20.1%), a - abundant (20–5.1%), Athabasca Glacier is positioned in Jasper National Park o - occasional (5–1%) and s - scarce (<1%). (10,878 km2), known as the largest National Park in the The standard literature was primarily used for species Canadian Rockies in Alberta. The geology of the site is re- identification (Krammer, and Lange-Bertalot 1986-2004, Diatom richness in glacial streams 75

Lange-Bertalot, and Krammer 1989, Lange-Bertalot, and Moser 1994, Lange-Bertalot, and Metzeltin 1996, Kram- mer 1997a/b, Lange-Bertalot 2001) since the largest part of diatoms were widely distributed especially the artic alpine (circumpolar) taxa. In some cases of doubtful identification, the Monography on the diatoms of the United States was consulted (Patrick, and Reimer 1966). The thorough work on Achnanthidium taxa was largely based on Potapova, and Ponader (2004), Potapova, and Hamilton (2007), Ponader, and Potapova (2007) and the new online diatom identification guide of diatoms of the US (Spaulding et al. 2010, http://westerndiatoms. colorado.edu). To provide taxonomic consistency with projects carried out in the US, terminology was based on the ANSP-2011 taxonomic system (The Academy of Natural Sciences of Philadelphia; Phycology Section, http://diatom.ansp.org/ taxaservice/). For those taxa not included in this list (9 taxa), taxa names were given according to Hofmann et al. (2011) and marked with an asterisk in the Appendix. For 2 taxa (Achnanthes pusilla, Achnanthes petersenii), we fol- lowed the taxonomy acc. to Hoffmann et al. (2011) and did not transfer them to the genus Rossithidium. The distance from the glacier and the percentage of glaciation was calculated from geographic maps. Statistical analysis was based on SPSS 18.0 analytic software. Squared Euclidean distance was used as a measure of similarity between all cases based on presence / absence data (all 118 species). Hierarchical cluster analysis of the 12 investigated sites was carried out with Ward’s linkage and Pearson’s correlation coefficient has been used to measure the strength of the association between diatom richness and catchment glaciation/distance from the glacier. Fig. 2. Light micrographs of 12 characteristic taxa from gla-cier streams of SW Canada; 1 - Hannaea arcus, 2-4 - Encyonema RESULTS minutum, 5 - Encyonema latens, 6 - Gomphonema calcifugum, 7 Diatom species spectrum - Meridion circulare, 8 - Karayevia oblongella, 9 - Achnanthid- ium kriegeri, 10 - Achnanthidium minutissimum, 11 - Psammoth- Diatom identification has yielded a total of 118 diatom idium grischunum; 12 - Diatoma mesodon, scale bar=10 mm. taxa belonging to 38 genera, several characteristic taxa are illustrated in Figs 2 and 3. The genera richest in diatom taxa were Achnanthes related taxa (21 taxa), Navicula related sites. The quantitatively dominating taxa at most sites taxa (14 taxa) and Cymbella related taxa (12 taxa). Gener- Achnanthidium minutissimum and Hannaea arcus were ally a high percentage of diatom taxa (65%, 77 taxa) oc- present in all the samples up to maximum relative abun- curred only once (41 taxa) or twice (36 taxa) in the data set. dances of 72% and 55%, respectively (Tab. 2). Species Most taxa found in this study (92%, 108 taxa) were numbers ranged from 16 in the upper site of Matier Glacier recorded in the ANSP-2011 taxonomic system (The Acad- creek (site 2) and in the site near Tszil Glacier mouth (site emy of Natural Sciences of Philadelphia; Phycology Sec- 6) to 50 in the outflow of the lowest Joffré Lake near the tion, http://diatom.ansp.org/ taxaservice/). The most parking lot (site 9) (Fig. 4). frequent taxa in the data set were the oligotraphentic taxa Those diatoms reaching more than 4% relative abun- Hannaea arcus, Achnanthidium minutissimum, Psammoth- dance in at least 1 sample (20 taxa) were chosen to repre- idium grischunum, Tabellaria flocculosa and the oligome- sent the species spectrum (Tab. 2). Besides Achnanthidium sotraphentic taxon Encyonema minutum (detected in at minutissimum and Hannaea arcus were several Achnan- least 83% of the samples). Firmly attached small specimens thes related taxa (6 taxa) and Encyonema (4 taxa) charac- of the genera Achnanthidium, Psammothidium, Ency- terizing the species spectrum. The oligo-mesotraphentic onema, Fragilaria and Gomphonema were common at all taxa Encyonema minutum and Encyonema silesiacum oc- 76 D. Gesierich, and E. Rott

curred in more than 2/3 of the sampling sites with maximum relative abundances of 6.8% and 11.0%, respectively. Encyonema latens was restricted to 3 sites only, most common at the Stonecrop Glacier site (site 4) with a relative abundance of 35.6%; this scarcely recorded taxon is known from Iceland, Spitzbergen, Alaska, Lake Michigan and the highlands of Venezuela (Krammer 1997a). Encyonema neogracile is restricted to two sites only, it was found in Tszil Glacier stream in higher abundances (11.2%). Several small and firmly attached species of Achnan- thes related taxa were found at all sites, but mainly or ex- clusively (15 taxa) in relative abundances <5%. The more frequent taxa Achnanthidium rivulare (5.8%) and Achnan- thidium kriegeri (8.7%) were mostly found near the Tszil Glacier mouth (site 6), the latter occurred also in the upper part of Matier Glacier creek (site 2) with a proportion of 12.1%. Psammothidium grischunum (24.4%) and Achnanthes pusillum (5.4%) were characterizing the diatom assemblage further downstream in Tszil Glacier stream (site 5). Achnanthes petersenii was the dominating taxon in Illecillewaet River (site 11) with a relative abundance of 65.8%, a rarely recorded taxon at calcareous oligotrophic (up to mesotrophic) sites. In addition to these taxa Gomphonema calcifugum (oligo-mesotraphentic) and Fragilaria vaucheriae as well as Diatoma ehrenbergii/D. vulgaris are worth mentioning, the latter were Fig. 3. Scanning electron micrographs of 6 characteristic taxa from restricted to Cayoosh Creek (site 10, 42.4% and 5.5%). site 4 (Stonecrop Glacier site) and 12 (Athabasca River) respec- Gomphonema calcifugum was found at various sites, tively, site numbers appear in brackets after the taxon name; 1 - reaching highest abundances near the Stonecrop glacier Hannaea arcus (12), 2+3 - Gomphonema calcifugum (4), 4 - Frag- (site 4, 25.4%), whereas Fragilaria vaucheriae was fre- ilaria vaucheriae (12), 5+6 - Achnanthidium minutissimum (4), 7 quent in the Upper Joffré Lake outlet (8.2%) and in - Encyonema latens (4), 8 - Psammothidium grischunum (4), scale bar = 5 µm (for numbers 1, 2, 7 the scale bar equals 10 mm). Athabasca River (6.5%). Trophic preferences were found from the literature for

Fig. 4. Hierarchical clustering of 3 major groups of sites according to their diatom species composition using Ward’s linkage together with some information on diatom richness (= total number of taxa incl. single individuals) and the site's distance from glacier. Diatom richness in glacial streams 77

Tab. 2. Diatom species composition of 12 Canadian glacier streams. Ordination of samples and species according to cluster analysis (sample cluster see Fig. 4; taxa with relative abundance >4% in at least 1 sample); abundances given as 5 abundance classes: e - eudominant (>50%); d - dominant (50-20.1%); a - abundant (20-5.1%); o - occasional (5-1%); s - scarce (<1%); for explanation of site numbers see Tab. 1. Site 12 6 11 10 374512 89 Hannaea arcus es a o o e d ao dd s Achnanthidium minutissimum ae e a a a a ad dd a Psammothidium grischunum oo o s s s o d ss s Encyonema minutum ao o s o o o a os s Tabellaria flocculosa so o s a s s os e Achnanthidium kriegeri oa a o s s o s Encyonema silesiacum sasaoass Meridion circulare asssssss Achnanthidium rivulare oa s ssss Gomphonema calcifugum ssdooos Achnanthes pusilla osasss Fragilaria vaucheriae oss aao Achnanthidium linearioides os s s Achnanthes petersenii eso Encyonema latens oda Encyonema neogracile oa Gomphonema olivaceum os Nitzschia fonticola os Diatoma ehrenbergii d Diatoma vulgaris a

78% of the diatom taxa (93 taxa). Half of the taxa (49%) sites were characterised by the highest diatom richness were classified as oligotraphentic (4% ultraoligo-traphen- within the Coast Mountain samples. The species spectrum tic, 27% oligotraphentic, 18% oligo-mesotraphentic) and from both sites showed beside typical stream taxa as mesotraphentic (16%), another 27% as mesoeutraphentic Achnanthidium minutissimum and Hannaea arcus, small (15%) and eutraphentic (12%). Only a very small propor- amounts of planktonic centric taxa (mostly Cyclotella tion was classified with a preference for eupolytraphentic species) and a dominance of Tabellaria flocculosa, a com- (5%) and polytraphentic conditions (2%) (Rott et al. mon littoral diatom, at the lower lake outlet (site 9). 1999). Based on the Red List of algae for Germany (Lange-Bertalot, and Steindorf 1996) 103 diatom taxa GROUP B – upper stream segments with different runoff (87%) could be classified with 21% (22 taxa) as endan- sources gered to various extend (critically endangered - 1 taxon, Group B was characterised by higher relative abun- strongly endangered - 1 taxon, endangered - 11 taxa, ex- dances of Achnanthidium minutissimum and Hannaea tremely rare - 6 taxa, potentially endangered - 3 taxa). A arcus accompanied by several taxa defining the sub- large proportion of arctic-alpine diatom species in the sub- groups. The small proportions of the crenophilous taxa dominant taxa was characterizing the data set. Meridion circulare and Diatoma mesodon as well as Tabellaria flocculosa, typical for low mineral content, in- Classification of sites based on diatom species composition dicated the influence of different runoff sources (ground From hierarchical cluster analysis of all sites based on water?). presence / absence data including all 118 species found, Sites 3 and 7 (Matier glacier creek lower part, Tszil stream downstream near lake) showed highest relative three distinct groups (A-C) of sites were classified (Fig. 4). This differentiation of the major groups displays characters abundances of Hannaea arcus dominating at site 3, but reflected mainly by the relative proportions of the different H. arcus accompanied by Diatoma mesodon, Tabellaria and silesiacum at Site 7. Site 4 fed hydrological stream types: lake outlet, glacial (kryal) flocculosa Encyonema by stonecrop rock glacier was characterised by Ency- streams and krenal (spring fed) streams, respectively. onema latens and Gomphonema calcifugum. The species spectrum at site 5 (Tszil stream NE) was dominated by GROUP A - lake outlets Achnanthidium minutissimum, Psammothidium The first group of sites, separated from the other sites grischunum and Encyonema neogracile, whereas at site on the first division level, was formed by the two lake out- 12 (Athabasca River) Achnanthidium minutissimum was lets of Middle and Lower Joffré Lakes (sites 8, 9). These prevailing together with Hannaea arcus. 78 D. Gesierich, and E. Rott

GROUP C - hypokryal/glaciorhithral stream segments (Achnanthidium jackii, Amphora inariensis, Encyonema , , and - All sites in Group C showed varying abundances of the mesianum Diploneis ovalis Staurosirella pinnata group). Encyonema mesianum is a rarely found taxon in typical stream taxa Achnanthidium minutissimum, Ency- oligotrophic, electrolyte-poor habitats in high alpine re- onema minutum and Hannaea arcus. Sites 1, 2 and 6 lo- gions. cated directly at or close by the glacier mouth (site 1 and 2 The most species rich group amongst the 35 taxa reach- adjacent to Matier Glacier, site 6 close to Tszil Glacier ing relative abundances <1% are the related mouth) were characterised by higher amounts of Achnan- Achnanthes taxa with 6 different genera (Psammothidium grischunum, thidium kriegeri and Psammothidium grischunum. Site 1 , , might have been influenced by spring (ground) water input P. helveticum Eucocconeis laevis Planothidium lanceolatum, P. dubium, Achnanthidium jackii, A. rivulare, indicated by higher abundances of Meridion circulare. Ad- Karayevia oblongella, Achnanthes pusillum) and Nitzschia jacent to these three hypokryal sites there was a grouping spp. (Nitzschia bryophila, N. cf. perminuta, N. dissipata, of site 11 (Illecillewaet River) and site 10 (Cayoosh Creek), N. fonticola, N. pura, N. sublinearis). both represented the most distant sites from the glacial outflow. Site 11 was dominated by the oligotraphentic taxon Achnanthes petersenii. Site 10 reflected changes of diatom communities along alpine rivers with a shift from small, adhesive taxa of the Achnanthes related taxa group (except Achn. minutissimum 12% rel. abundance at site 10) to a dominance of the chainforming taxa Diatoma spp. (Di- atoma ehrenbergii dominant, D. vulgaris) and a sub-dominance of Encyonema spp. (Encyonema silesiacum, Encyonema minutum), Nitzschia spp. (Nitzschia fonticola, Nitzschia dissipata), Fragilaria vaucheriae, Reimeria sinuata and Gomphonema olivaceum (these 9 taxa account for 80% rel. abundance).

Longitudinal variation in species richness For analysing the relationship between diatom species richness and glaciation of the catchment as well as distance from glacier, sites 1 to 6 in Joffré Lakes Provincial Park have been chosen, for their geographic position is <1 km from the glacier mouth (Fig. 1). The existing lake basin downstream the Upper Joffré Lake had a specific effect in alteration of diatom species composition, therefore site 8, Fig. 5. Relationship between total species richness of diatoms although less than 1 km from the glacier mouth, was ex- and distance from glacier mouth in km for the 6 glacial stream cluded from the data set. The total number of diatoms sites in Joffré Lakes Provincial Park at distances of <1 km from species for the small streams close to the glacier mouth dis- the glacier mouth (sites 1 to 6); r– Pearson’s Correlation Coef- played a significant positive relationship with distance from ficient, *=significant (p<0.05). the glacier (Fig. 5) irrespective of catchment glaciation (r=0.176).

The Athabasca River origin – a special habitat Tab. 3. Diatom composition (>1% relative abundance) and their The taxa richness in Athabasca River at the glacier relative abundance (%) from Athabasca River origin at Colum- mouth (site 12) exceeded the expected results from the Aus- bia ice field. trian Alps with 43 diatom taxa recorded. It is most likely Taxon % that the actual number of diatoms may be even higher than Achnanthidium minutissimum 30.8 the one detected, since most of the taxa were detected only Hannaea arcus 25.9 once in the slide (59%, 26 taxa). Nine species occurred in Encyonema latens 8.7 relative abundances >1% with Achnanthidium Encyonema silesiacum 8.2 minutissi- Fragilaria vaucheriae 6.5 mum dominating, accompanied by the rheophilous taxon Encyonema minutum 2.7 Hannaea arcus, the nordic taxon Encyonema latens, Ency- Gomphonema calcifugum 1.9 onema silesiacum and Fragilaria vaucheriae (Tab. 3). Fragilaria tenera 1.6 Five taxa were restricted to this glacial outflow Tabellaria flocculosa 1.1 Diatom richness in glacial streams 79

DISCUSSION including several characteristic taxa e.g. Achnanthidium , , , The findings from Canadian glacial streams confirmed minutissimum Diatoma mesodon Encyonema minutum our hypothesis that environmental conditions in turbid gla- Gomphonema calcifugum, Hannaea arcus, Meridion cir- cial streams seem to select specific attached algal commu- culare and Staurosirella pinnata (Rott et al. 2006). A similarity of the characteristic taxa was even found nities (Gesierich, and Rott 2004). Although rarely recorded when the present results were compared with the algal until now (e.g., Jüttner et al. 2000; Cantonati et al. 2001; species records for the spring streams in the Great Smoky Gesierich, and Rott 2004; Rott et al. 2006), diatoms were well represented in all types of glacier streams even with Mountains National Park (Johansen et al. 2004) with a peak flows in summer (with very variable runoff!) and very lower proportion of 32% taxa in common. Specific arctic- close to the glacier mouth. alpine elements of the diatom flora (Achnanthes petersenii, The dominant species found in the Canadian glacier Encyonema latens and Gomphonema calcifugum) seemed streams corresponded in most cases to findings from other to be common not only in glacier streams but also in arctic glaciated mountain areas worldwide with two dominants: meltwater streams and small brooks (Van de Vijver et al. the pioneer taxon Achnanthidium minutissimum together 2003) as well as in moss samples and shallow lotic sites with low current (pre-sumably being able to survive periods with the rheobiontic Hannaea arcus (e.g., Cantonati et al. 2001), but contrasted to cryoconite holes dominated by of desiccation, Antoniades, and Douglas 2002). Encyonema other diatom taxa (e.g. Diadesmis, Mayamaea, Navicula, latens was also reported from a glacial pool formed by Luticola, Muelleria) more related to still water situations flooding of the surrounding area at high meltwater input (Müllner et al. 2001; Yallop, and Anesio 2010). The nomi- from a glacial stream in the arctic (Elster et al. 1997), nate variety of the rheobiontic Hannaea arcus however is whereas Gomphonema calcifugum was prevailing at some not an exclusive taxon of glacier streams since it was com- sites in the Himalaya together with Diatoma mesodon mon in most other fast flowing streams in arctic, antarctic (Cantonati et al. 2001). and Alaska (Milner et al. 1992; Beyens, and van de Vijver It is known that algal assemblages are partly regulated 2000). We did not encounter the expected variety recta of by catchment characteristics (Pipp, and Rott 1993; Rott et Hannaea arcus, although reported as fairly common for al. 1997, 1999; Rott et al. 2006). Geology however seemed cold circumpolar situations and the Himalaya region (Can- not to be of primary importance in these Canadian streams, tonati et al. 2001). Although Achnanthidium minutissimum since high variability of catchment glaciation and funda- is supposed to be a widespread taxon, it comprises a variety mentally different geological conditions between the Coast of ecomorphs that have specific adaptive capacities to grow Range sites and the Rocky Mountain sites showed a quite under oligotrophic cold water conditions (Potapova, and similar diatom composition. Although clear changes of the Hamilton 2007 - 6 morphotypes of A. minutissimum within diatom flora along the river continuum were observed in a data set of 728 specimens of North American Rivers). the Coast range, it was not primarily the size of the glacier Since the major taxonomic revisions of the Achnanthes – and the geology but the site’s distance from the glacier and related taxa, information on the autecological and biogeo- the related changes in the hydrological regime that shaped graphical distribution of the new taxa is scarce. The pres- diatom species composition most. ence of several Achnanthes related taxa (Achnanthes, Apparently in those glacier streams, larger already at Achnanthidium, Eucocconeis, Karayevia, Planothidium, the outflow of the glacier, fast current and strong flow vari- Psammothidium) with variable ecological demands in the ations accounted for a more diverse community (see streams observed seemed to underpin the specific situation Athabasca River). Hydrology in turbid glacier streams in- found here. For example, Achnanthidium minutissimum cluding scouring by sediment load may have had a negative present at all sites, is preferring low nutrient and ionic con- effect on benthic algal growth and species selection, tent, whereas Achnanthidium rivulare, found with slightly whereas nutrient input (generally phosphorus), mainly higher abundances in two sites in the Coast Range, is washed out as glacial flour (produced by the mechanical mainly recorded from low calcium, high chloride, phos- action of the glacier ice to the ground) positively affected phorus poor soft waters (Potapova, and Ponader 2004; Pon- algae species in the Alps and other mountain ranges in ader, and Potapova 2007). moderate latitudes (Bürgi et al. 2003; Gesierich, and Rott Despite high variability of catchment glaciation and 2004; Rott et al. 2006; Uehlinger et al. 2010). 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APPENDIX Overall diatom species list (118 taxa) including relative abundances (%) at sites 1-12 in SW-Canada; red list classification (RL) according to Lange-Bertalot, and Steindorf (1996) and trophic indication values (T) according to Rott et al. (1999); 1 – threatened with extinction; 2 - severly endangered 3 – endangered, G - probably endangered, R - rare, V – decreasing, * - at present not considered threatened, ** - surely not threatened, ● - to be expected within the area, D – data scarce; uo – ultraoligotraphentic, o – oligotraphentic, om – oligo- mesotraphentic, m – mesotraphentic, me – mesoeutraphentic, e – eutraphentic, ep – eupolytraphentic, p – polytraphentic; taxa names acc. to ANSP-2011 taxonomic system, taxa names marked with an asterisk are taken from Hofmann et al. (2011).

Taxon RL T1 2 3 4 5 6 7 8910 11 12 Achnanthes related taxa Achnanthes acidoclinata Lange-Bertalot 0.3 0.6 Achnanthes petersenii Hustedt 0.3 1.3 65.8 Achnanthes pusilla (Grunow) DeToni 3o 0.3 5.4 2.9 0.3 0.3 0.5 Achnanthes trinodis (Ralfs) Grunow 3o0.3 0.3 Achnanthidium caledonicum (Lange-Bertalot) Lange-Bertalot 3o 0.7 0.9 Achnanthidium jackii Rabenhorst D om 0.8 Achnanthidium kriegeri (Krasske) Hamilton, Antoniades, and Siver ● 1.9 12.1 0.3 1.6 8.7 0.9 0.3 3.6 Achnanthidium linearioides (Lange-Bertalot) Lange-Bertalot* 3m 4.6 0.3 0.3 0.3 Achnanthidium minutissimum (Kützing) Czarnecki ** om 16.6 72.2 9.9 8.0 25.0 58.3 17.3 48.9 7.5 12.1 17.9 30.8 Achnanthidium pyrenaicum (Hustedt) Kobayashi ** om 0.3 1.3 Achnanthidium rivulare Potapova, and Ponader 3.3 0.3 0.3 0.3 5.8 0.3 0.5 Eucocconeis flexella (Kützing) Cleve 3 uo 0.3 Eucocconeis laevis (Østrup) Lange-Bertalot * om 0.3 0.3 0.3 0.3 Karayevia oblongella (Østrup) Aboal Vo0.3 1.0 1.0 0.3 0.3 Planothidium delicatulum (Kützing) Round, and Bukhtiyarova *e 0.3 Planothidium dubium (Grunow) Round, and Bukhtiyarova * 0.3 0.3 0.5 Planothidium lanceolatum (Brebisson ex Kützing) Lange-Bertalot ** ep 0.3 0.3 0.3 Psammothidium grischunum (Wuthrich) Bukhtiyarova, and Round * 2.6 1.6 0.3 4.6 24.4 3.9 0.6 0.3 0.3 0.7 0.5 Psammothidium helveticum (Hustedt) Bukhtiyarova, and Round *o 0.3 1.0 0.3 0.3 Psammothidium rechtensis (Leclercq) Lange-Bertalot R om 1.6 0.3 Psammothidium subatomoides (Hustedt) Bukhtiyarova, and Round V me 0.3 Amphora inariensis Krammer 3 me 0.3 Amphora pediculus (Kützing) Grunow ** e 0.3 0.3 Aulacoseira cf. italica (Ehrenberg) Simonsen V 0.3 0.3 Brachysira brebissonii Ross * om 0.3 Brachysira neoexilis Lange-Bertalot* * om 0.3 0.3 0.7 Brachysira sp. 0.3 0.3 Brachysira vitrea (Grunow) Ross 3o0.3 0.3 Caloneis cf. ventricosa var. truncatula (Grunow) Meister 1.2 Cocconeis neodiminuta Krammer R 0.3 Cocconeis placentula Ehrenberg ** e 0.3 0.3 Cocconeis placentula var. lineata (Ehrenberg) Van Heurck ** me 0.3 Cyclotella ocellata Pantocsek * om 0.3 0.3 2.6 Cyclotella pseudostelligera Hustedt* ** 1.1 Cymbella related taxa Cymbella amphicephala Nägeli V om 0.3 Cymbella cistula (Ehrenberg) Kirchner V me 0.3 0.3 Cymbella helvetica (Kützing) V om 1.1 Encyonema gaeumannii (Meister) Krammer 3o 0.7 Encyonema latens (Krasske) Mann ● 2.5 35.6 8.7 Encyonema mesianum (Cholnoky) Mann Vm 0.3 Encyonema minutum (Hilse) Mann *m6.8 1.0 3.7 5.4 1.9 1.6 0.6 0.3 3.9 0.3 2.7 (continued) Diatom richness in glacial streams 83

APPENDIX: Continuation Taxon RL T1 2 3 4 5 6 7 8910 11 12 Encyonema neogracile Krammer 3o 11.2 1.0 Encyonema silesiacum (Bleisch) Mann *m0.6 0.3 3.4 11.0 0.3 0.3 9.2 8.2 Encyonopsis cesatii (Rabenhorst) Krammer *o 0.3 0.3 1.6 0.3 Encyonopsis microcephala (Grunow) Krammer * om 0.3 Reimeria sinuata (Gregory) Kociolek, and Stoermer ** me 0.3 0.3 0.3 2.9 0.8 Diatoma anceps (Ehrenberg) Kirchner * uo 0.3 0.3 0.3 Diatoma ehrenbergii Kützing ** m 42.4 Diatoma mesodon (Ehrenberg) Kützing *o 0.6 2.2 1.9 6.0 0.3 0.3 0.5 Diatoma vulgaris Bory Dm 5.5 Didymosphenia geminata (Lyngbye) Schmidt 1o 0.3 Diploneis ovalis (Hilse) Cleve Vo 0.3 Diploneis sp. 0.3 0.3 Eunotia bilunaris (Ehrenberg) Souza ** o 0.3 0.3 0.3 Eunotia cf. paludosa Grunow V 0.6 0.3 0.3 2.6 1.9 0.3 0.3 Eunotia exigua (Brébisson) Rabenhorst ** uo 0.3 0.3 Eunotia implicata Nörpel, Alles, and Lange-Bertalot Go 0.3 0.3 Eunotia incisa Smith ex Gregory *o 1.6 Eunotia minor (Kützing) Grunow *e 0.3 Eunotia muscicola Krasske ● 0.3 Fragilaria related taxa Fragilaria capucina Desmazieres ** m 0.3 0.3 1.0 0.6 Fragilaria tenera (Smith) Lange-Bertalot Vo0.3 0.3 1.9 0.3 0.3 0.3 1.6 Fragilaria vaucheriae (Kützing) Petersen ** m 0.6 0.3 8.2 1.4 4.2 6.5 Hannaea arcus (Ehrenberg) Patrick ** o 55.5 0.7 81.1 6.2 4.8 6.8 41.8 27.8 0.6 2.1 2.3 25.9 Pseudostaurosira brevistriata (Grunow) Williams, and Round ** e 0.3 0.3 Staurosirella pinnata – Group (Ehrenberg) Williams, and Round ** me 0.3 Synedra rumpens Kützing *o0.3 0.3 0.6 2.0 0.7 Ulnaria ulna (Nitzsch) P. Compére * ep 0.3 Frustulia rhomboides (Ehrenberg) De Toni* uo 0.3 0.3 2.0 Gomphonema acuminatum Ehrenberg ** me 0.3 0.3 Gomphonema affine Kützing Rm 0.3 0.3 Gomphonema angustatum (Kützing) Rabenhorst *o 1.6 0.3 0.3 0.3 0.3 Gomphonema cf. bipunctatum Krasske* R 1.0 Gomphonema cf. instabilis Hohn et Hellermann* 0.3 0.3 Gomphonema micropus Kützing *m 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Gomphonema olivaceum (Lyngbye) Kützing ** e 4.2 0.3 Gomphonema calcifugum Lange-Bertalot et Reichardt* * om 0.3 25.4 2.6 0.3 1.4 0.3 1.9 Gomphonema parvulum (Kützing) Kützing e 0.3 0.5 Meridion circulare (Greville) Agardh ** me 12.0 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Meridion circulare var. constrictum (Ralfs) Van Heurck ** om 0.3 0.3 Navicula related taxa Cavinula pseudoscutiformis (Hustedt) Mann, and Stickle 3 om 0.3 Diadesmis perpusilla (Grunow) Mann ** om 0.3 0.3 0.3 Luticola mutica (Kützing) Mann ** e 0.3 0.3 0.3 Luticola ventricosa (Kützing) D.G. Mann D ep 1.0 Mayamaea atomus (Kützing) Lange-Bertalot ** p 0.3 0.3 0.3 Navicula cari Ehrenberg ** e 0.3 Navicula cf. concentrica Carter et Bailey-Watts 2 0.3 Navicula cf. cryptocephala Kützing ** ep 0.3 Navicula cryptotenella Lange-Bertalot me 0.3 0.3 0.3 0.3 0.3 Navicula elginensis (Gregory) Ralfs* * me 0.3 Navicula lanceolata (Agardh) Kützing ** ep 0.3 Navicula radiosa Kützing ** o 0.3 1.8 Navicula rhynchocephala Kützing ** me 0.3 Navicula sp. 1.0 0.3 Neidium ampliatum (Ehrenberg) Krammer V om 0.3 Neidium bisulcatum (Lagerstedt) Cleve 3o 1.3 Nitzschia angustata (Smith) Grunow *m 0.3 0.3 Nitzschia bryophila (Hustedt) Hustedt G 0.3 0.3 Nitzschia cf. perminuta (Grunow) Peragallo * me 0.6 0.3 0.3 1.9 0.6 0.3 0.3 0.3 Nitzschia dissipata (Kützing) Grunow ** me 1.9 0.3 0.3 2.4 0.3 Nitzschia fonticola (Grunow) Grunow ** m 4.7 0.5 Nitzschia gracilis Hantzsch * me 0.3 0.3 Nitzschia pura Hustedt *m 0.3 0.6 0.3 Nitzschia recta Hantzsch ex Rabenhorst ** e 0.3 Nitzschia sublinearis Hustedt *e 0.3 0.3 Pinnularia biceps Gregory 0.3 Pinnularia borealis Ehrenberg m 1.0 0.3 Pinnularia cf. appendiculata (Agardh) Cleve *m 0.3 0.3 Pinnularia cf. julma Krammer, and Metzeltin* 0.3 Pinnularia cf. rupestris Hantzsch Go 0.3 Pinnularia hilseana Janisch 0.3 0.3 Pinnularia microstauron (Ehrenberg) Cleve Vo 0.3 Pinnularia subcapitata Gregory *o 0.3 1.3 Stauroneis cf. alpina Hustedt R 1.6 0.3 Stauroneis cf. prominula (Grunow) Hustedt R 0.3 0.3 Surirella angusta Kützing *p 0.3 0.3 0.6 0.3 Tabellaria fenestrata (Lyngbye) Kützing V om 0.3 1.4 Tabellaria flocculosa (Roth) Kützing ** o 0.3 1.0 0.3 0.6 0.3 10.4 0.3 73.7 1.0 1.1